NOTE: not been tested, YET.

Updated version:
Previous version jammed as soon material entered the pump, so i geared it down. Also the coupling mechanism is different. It makes the whole thing more compact.

Rotor diameter has been doubled, inlet is redesigned. Also i designed a few moulds to make silicone sealings. One between motor and spacer, the other around the motor axis, behind the coupler and between the inlet/spacer and inlet/stator.

Vitamins:

• 4x Threaded rod M4 x 45mm
• 1x Bearing 8x22x7
• 3x Screws M3x10
• 1x Hexcap M8 x 18mm (cut it to length)
• 2x Hexcap M4 x 16
• 1x Nut M8
• 9x Nut M4
• 2x M8 washers (printed, to height needed)

Assembly:
The whole assembly is clamped by four M4 threaded rods and nuts. The stator has a few holes that need drilling. Motor is mounted with M3x10mm screws. The nut that is inserted in oldham_1.stl need a M3 hole drilled in the side, after that you cut threads for the M4 hexcap. Insert the M8 screw through the gear and bearing, screw on oldham_1 and secure with the M4 screw :) The rest of it is obvious, i think.

Important
Inside the motor mount is a 8x22x7 bearing, you have to insert this mid-print, edit your G-code after slicing, search for the layer that is going to cover the bearing. Directly after G1 Zxx.xxx you put the folowing code:

G1 X90.000 F1200 ;move extruder to the side
G4 S60 ;dwell, wait for one minute, additionally you can pause the print in host.
G1 E20.000 F100 ;prime extruder after pausing
M220 S50 ;slow down, plastic doesnt like to stick to metal.
 

After printing an layer of proper quality readjust speed with M220 S100. This method is also used in oldham_1.stl. Insert a M8 nut before closing the hole, it prevents bridges. M220 is supported on Marlin, try if its working on your firmware :)